Download

Download the latest image from one of the following channels.

Download here

Extracting

muOS images are distributed as .img.gz files and most imaging software shouldn’t require them to be extracted.

SD Card Quality

Please make sure that you flash any CFW on a quality SD card. This will ensure your data stays safe and doesn’t fail on you in the middle of catching that rare Pokémon! Samsung and Sandisk cards are recommended.

Flashing

There are several recommended programs you can use to flash your SD card

Raspberry Pi Imager

After countless flashes we have determined that the most user friendly tool with the highest chance of success is Raspberry Pi Imager so we’ll focus on that for now.

   
Choose Device No Filtering
Choose Use Custom OS Select the muOS .img.gz
Choose SD Card Reader Click Next
No OS Customisation Yes Erase SD Card
Approve Elevation Card begins Writing
Verify Begins Eject and insert into console

Advanced Flashing

If you’re not afraid of using command line tools you can use dd to get the job done. You will need to find out what device path your SD card is located. Make sure to replace sd_device with your SD card device location and muos_image with the image name.

gunzip -c < "image_name_here.img.gz" | sudo dd of=/dev/sdxyz bs=4M conv=fsync status=progress

For MacOS users (determine your SD card label with diskutil GUI or diskutil list command and replace the X in /dev/diskX):

# To get rid of "dd: /dev/rdiskX: Resource busy"
sudo diskutil unmountDisk force /dev/diskX

# For best performance use the "RAW" device:
sudo dd if=/path/to/image_name_here.img of=/dev/rdiskX bs=4M status=progress && sync

Finishing Up

Once flashing to an SD card is successful you can put it in your device and switch it on It will run through a few menus to help get setup first and it will then do the rest of the setup for you. This will create all the needed files and folders for you to put your favourite content on.

Be Patient

If you find that your device is stuck during “Factory Reset” please give it at least 5-10 minutes before hitting the reset button. This should not happen, but if it does please make a post in the Discord issues channel.

Updating An Existing Install

Currently, muOS only supports updating versions by re-flashing the SD card, which can erase important data if you’re not careful!

A second SD can be used to preserve ROM files, but keep in mind that save data and configuration are still on SD1. To preserve this data, use the backup feature built into muOS. On 2405.1 and above, this is under the Task Toolkit menu.

  1. Create a backup .zip file from the muOS menu and store it on an external device.
  2. If using a single SD card, back up all ROM files.
  3. When you are CERTAIN that your data is safe, proceed with the flashing and installation method above.
  4. Unzip the backup in the root of SD1 ROMS/ partition, so that the folders merge with one another.
  5. If using a single SD card, copy ROM files back onto the SD Card.